Her Majesty the Queen in Right of Canada, As Represented by the Minister of Agriculture and Agri-food

Her Majesty in Right of Canada As Represented by the Minister of Agriculture and Agri-food Canada

Kevin L Rozwadowski

Derek J Lydiate

The invention provides methods of modifying the level of expression or functional activity of factors such as enzymes or other catalytic proteins or structural proteins, alone or in concert, to modify the frequency of meiotic homologous recombination involving the exchange of genetic information between non-sister chromatids from homologous maternal and paternal chromosomes. The steps at which modulation may occur include: homologous chromosome pairing, double-strand break formation; resection; strand invasion; branch migration; and resolution. Methods of plant and animal breeding are also provided that utilize the modulation of meiotic homologous recombination.

Modulation of meiotic recombination

The invention provides methods and nucleic acid constructs that may be used to modify a nucleic acid of interest at a target locus within the genome of a host. In some aspects, the invention contemplates producing in vivo a gene targeting substrate (GTS), which may be comprised of both DNA and RNA components. The gene targeting substrate may comprise a gene targeting nucleotide sequence (GTNS), which is homologous to the target locus, but comprises a sequence modification compared to the target locus. The gene targeting substrate may be produced by reverse transcription of a gene targeting message RNA (gtmRNA). The gene targeting message RNA may be folded for self-priming for reverse transcription by a reverse transcriptase. The gene targeting message RNA may in turn be the product of transcription of a gene targeting construct (GTC) encoding the gene targeting message RNA. The gene targeting construct may for example be a DNA sequence integrated into the genome of the host, or integrated into an extrachromosomal element. Following expression of the gene targeting systems of the invention, hosts may for example be selected having genomic modifications at a target locus that correspond to the sequence modification present on the gene targeting nucleotide sequence. In some embodiments, the structure of retrons may be adapted for use in the gene targeting systems of the invention.

Retrons for gene targeting

The present invention provides methods of modifying in vivo mutagenesis or homologous and homeologous recombination in a eukaryote. The method of modifying in vivo mutagenesis involves transforming a eukaryote with a nucleotide sequence capable of expressing a wild-type prokaryotic MutS, MutL, MutH, MutU, NLS-MutS, NLS-MutL, NLS-MutH, NLS-MutU protein, or a combination thereof, and expressing the protein. A method of modifying recombination between homologous chromosomes in an allopolyploid eukaryotic organism comprising, expressing a nucleotide sequence encoding prokaryotic NLS-MutS in combination with one or more than one of NLS-MutL, NLS-MutH, or NLS-MutU, within a germ cell of the allopolyploid eukaryotic organism is also disclosed.

Modifying the DNA recombination potential in eukaryotes

The present invention provides methods of modifying in vivo mutagenesis or homeologous recombination in a eukaryote. The method of modifying in vivo mutagenesis involves transforming a eukaryote with a nucleotide sequence capable of expressing a wild-type prokaryotic MutS, MutL, MutH, MutU, NLS-MutS, NLS-MutL, NLS-MutH, NLS-MutU protein, or a combination thereof, and expressing the protein. A method of modifying recombination between homeologous chromosomes in an allopolyploid eukaryotic organism comprising, expressing a nucleotide sequence encoding prokaryotic NLS-MutS in combination with one or more than one of NLS-MutL, NLS-MutH, NLS-MutU, within a germ cell of the allopolyploid eukaryotic organism is also disclosed.

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Saskatoon, Canada

Kevin L Rozwadowski